scrub wedged (both running and not running at the same time)

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I can't start a scrub because it is running, and can't cancel it because it isn't running! How do I get out of this state? OS is Ubuntu 14.10.

$ uname -r
3.16.0-28-generic

# btrfs scrub start .
ERROR: scrub is already running.
To cancel use 'btrfs scrub cancel .'.
To see the status use 'btrfs scrub status [-d] .'.
# btrfs scrub cancel .
ERROR: scrub cancel failed on .: not running
# btrfs scrub status .
scrub status for b02cc605-dd78-40bc-98a5-8f5543d83b66
	scrub started at Mon Nov 17 20:27:17 2014, running for 64491 seconds
	total bytes scrubbed: 3.43GiB with 1 errors
	error details: read=1
	corrected errors: 1, uncorrectable errors: 0, unverified errors: 0

Even a reboot doesn't make this go away.

Roger
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iEYEARECAAYFAlSnL88ACgkQmOOfHg372QTpogCgvOpEAjIQI5dq+QPtRPty1gB/ 3q0An0llPrQkIeDprwiH4pRBzuZdWdRg
=NXGR
-----END PGP SIGNATURE-----

This has been fixed in btrfs-progs 3.16.2 by commit d5fd05a773e2b19455be7e1208e9003a607483c6

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Thanks. I cloned and built the latest stable btrfs-progs and scrub now works on that filesystem as expected.

Roger

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iEYEARECAAYFAlSpv3IACgkQmOOfHg372QQfrACffGNwaoZZOwiQpsOc1eu6LBYW 2CYAn0v1aNq1zyenW2sBfz2JZyPvWBmK
=8Ekg
-----END PGP SIGNATURE-----